Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C25/00—Alloys based on beryllium
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
  • G21C3/02—Fuel elements
  • G21C3/04—Constructional details
  • G21C3/06—Casings; Jackets
  • G21C3/07—Casings; Jackets characterised by their material, e.g. alloys
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E30/00—Energy generation of nuclear origin
  • Y02E30/30—Nuclear fission reactors
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S376/00—Induced nuclear reactions: processes, systems, and elements
  • Y10S376/90—Particular material or material shapes for fission reactors

Definitions

• This invention relates to a novel beryllium alloy which is intended for use at high temperature in an oxidizing atmosphere.
• This novel alloy is particularly suited for use in the hot zones of nuclear reactors in which the removal of heat is carried out by circulation of carbon dioxide gas.
• the structural elements of a reactor of this type are subjected to the eflects of elevated temperature, of mechanical stresses, of corrosion by carbon dioxide gas and of neutron bombardment.
• the binary alloy which contains 0.05% to 3% calcium as described in French Pat. No. 1,307,236 granted to Associated Electrical Industries on Dec. 1, 1961, exhibits satisfactory behavior in carbon dioxide gas up to 700 C. but reveals in the first place that an improvement in the mechanical properties and creep strength at high temperatures would be desirable and in the second place that it is rapidly embrittled under the action of neutrons.
• a micrography of a beryllium alloy containing either one or a number of the addition elements mentioned above shows a large number of intermetallic precipitates whose presence within the matrix explains the hardening effect which is obtained.
• Embrittlement of beryllium and beryllium alloys under exposure to radiation is caused by gases (mainly helium) which are generated in the metal under the action of neutrons according to the following reactions:
• the gas atoms which initially occupy positions adjacent to those of the beryllium atoms from which they are derived migrate and finally collect in the form of bubbles in the grain boundaries and also in the matrix.
• the bubbles of the grain boundaries will increase in size as a result of creation of lattice vacancies and will result in total decohesion of the boundaries.
• One of the objects of this invention is to provide a means for obtaining this result.
• the present applicant has in fact found that the intermetallic precipitates set up an obstacle to the motion of gas bubbles within the irradiated beryllium matrix. Moreover, said precipitates are correspondingly more eifective as they have a smaller grain size, are more numerous and more uniformly distributed.
• the alloys in accordance with the invention can be fabricated by means of known powder metallurgy techniques, the powder being obtained by comminution of flakes obtained by lathe turning of cast ingots. Said ingots can be fabricated from a metal which may or may not have been electrolytically produced. However, a preferred method of fabrication consists of vacuum melting followed by direct conversion of the ingot by extrusion, forging or rolling.
• alloys D and E are in accordance with the present invention: the alloy D contains 0.4% Ca and 0.5% Pd; the alloy E contains 0.4% Ca and 0.2% Fe.
• All these alloys except A have been fabricated by vacuum melting in an induction furnace of a mixture of electrolytically produced beryllium flakes and of previously prepared master alloys Be-Ca, Be-Fe, Be-Pd. The cast billets thus obtained were then converted to round rods by press extrusion.
• Iron is an inevitable impurity of beryllium and particularly of sintered products since the attrition mills are mostly constructed of steel.
• the iron content does not usually exceed 300 p.p.m. in the case of electrolytically produced flakes, 800 p.p.m. in the case of the powder obtained from these flakes and 1500 p.p.m. in the case of a powder obtained from a metal prepared by the magnesiothermic reduction process.
• Table I gives the ultimate strengths and the elongations at fracture of alloys D and E in the extruded state and annealed (one hour at 800 C.) in respect of different temperatures. Very closely related values have been obtained in the as-extruded state, in the stabilized state (500 hrs. at 575 C.), in the hardened and tempered state.
• the additions of Pd and Fe increase the ultimate strengths of the 0.4% Ca alloy to a greater extent than is achieved by the addition of Zr and the same applies 4 to An, Pt, Ir, Rh.
• Test temperature in C 400 500 600 Table III gives a few of the values which have been weight of calcium and 0.15 3% by weight of at least foulldlll respect f grain SiZe, number and SlZe P grams 0f one addition metal selected from the group comprising precipitate per unit of volume as compared with the best 4 iron, n di m, gold, platinum iridium rhodium the a 1 o 3 J 3 values obtamed the case of the bmary Be ca alloy remainder being essentially constituted by beryllium.
• An alloy in accordance with claim 2 wherein the 'Embrittlement of irradiated beryllium at high temperproportion of said additional metal is Within the range ature is mainly exhibited at the time of application of of 0.15 to 1% by weight. a stress which causes an increase in size of the helium 7.
• An alloy in accordance with claim 2 comprising bubbles within the grain boundaries. The following method 0.15 to 0.5% by weight of iron.

Landscapes

• Engineering & Computer Science (AREA)
• Metallurgy (AREA)
• Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Plasma & Fusion (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Organic Chemistry (AREA)
• Powder Metallurgy (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=8655477

Family Applications (1)

Country Status (7)

Cited By (1)

• 1968
  • 1968-10-09 FR FR169330A patent/FR1585351A/fr not_active Expired
• 1969
  • 1969-10-01 AT AT927769A patent/AT291609B/de not_active IP Right Cessation
  • 1969-10-01 NL NL6914827A patent/NL6914827A/xx unknown
  • 1969-10-02 US US863327A patent/US3685988A/en not_active Expired - Lifetime
  • 1969-10-07 LU LU59590D patent/LU59590A1/xx unknown
  • 1969-10-09 BE BE740005D patent/BE740005A/xx unknown
  • 1969-10-09 DE DE19691950973 patent/DE1950973B2/de active Pending

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